Microporous membranes are commonly made of polyolefins and are used in numerous end use applications such as medical and industrial filtration, battery separator membranes, separation methods, deaeration, water and fluid purification, etc. Such membranes are available from Celgard, LLC of Charlotte, N.C. Due to their chemical nature, polyolefin microporous membranes are hydrophobic and repel water. While water in the liquid state is repelled by polyolefin porous membranes, water vapor molecules in their gaseous state are able to permeate into the porous structure of the membrane and pass through its pores.
Microporous membranes that are water impermeable and air permeable could be useful as materials for waterproof/breathable textile materials and apparel including footwear, as well as in certain industrial applications, such as building construction, where a combination of waterproofness and breathability may be desirable. Such membranes are available from Celgard, LLC of Charlotte, N.C.
A need exists for such membranes for at least certain uses or applications to not only have waterproofness and breathability, but also to have increased mechanical strength to withstand the rigors of repeated use, a degree of stretch and recovery to enhance wearer comfort or to improve the membrane's conformability to twists and bends, and/or to have improved ‘hand’ or drape.